1. Field of the Invention
The invention herein relates to flow valves for internal combustion engines. More particularly, it relates to barrel type rotary valves for such engines.
2. Description of the Prior Art
Rotary valves for internal combustion engines have been known for many years. They are classified for two types: a ported disk with its axis parallel to the center line of the cylinder bore or a ported drum or barrel with its axis at right angles to the cylinder. An example of the former is shown in U.S. Pat. No. 4,776,306. The rotary valve of the present invention is an example of the latter type. The two types are distinctly different and are subject to significantly different operating characteristics and problems.
Particular problems arising with barrel type rotary valves include leakage of gas around the outside of the valve. These problems include leakage of gas between intake and exhaust passages (in dual function valves), sealing against gas passage from between adjacent cylinders and efficiency of the combustion (from poor combustion chamber shape and the attendant poor placement of the spark plug) and significant friction losses from the lack of presence of bearings capable of operating in the severe operating environment.
Both two cycle and four cycle internal combustion engines have, of course, also been known for many years. Two cycle engines themselves are divided into two categories, those which have crank case scavenging of the exhaust gases and those which have positive external scavenging. Two cycle engines have the advantage of being smaller and lighter and could, therefore, be advantageously used in small vehicles such as automobiles, light trucks, and motorcycles. However, for the last few years two cycle engines have been incapable of generating sufficient power for vehicular use while simultaneously meeting government vehicle emissions requirements. Consequently, in recent years, spark ignition vehicle engines have been uniformly four cycle engines.
More recently, however, a number of engine and automobile manufacturers have developed and tested several new designs of two cycle engines for vehicles, which engines are described as being of increased power while yet having emission levels low enough to meet government specifications. Consequently, significant interest in the use of two cycle engines for motor vehicles has again developed.
It would, therefore, be very advantageous to have a design of a rotary valve which would be an efficient valve mechanism and would be equally applicable to use with both two cycle and four cycle engines. Such rotary valves would necessarily be much superior to conventional poppet valves in engines, especially in two cycle engines, since poppet valve mechanisms have relatively low operation rates and thus engines have to be slowed down in order for the poppet valves to keep up and operate properly. The rotary valves, however, would be high speed mechanisms and therefore the engines could run at much higher speeds without valve limitations.